1. Field of the Invention
The present invention relates to a transfer device for transferring a cargo, and a carrier system provided with this device.
2. Description of the Related Art
There is known a carrier system for carrying and transferring a cargo by means of a carrier that travels along a rail arranged on the ceiling side. The carrier has a travelling vehicle that travels along a rail arranged on the ceiling side, and a lift stage that is lifted or lowered while being hung from the travelling vehicle. Below the rail, there is installed a rack arranged with a plurality of stages of storage shelves for storing cargos.
The lift stage is provided with a transfer device for transferring a cargo between the lift stage and the storage shelf (e.g., Unexamined Japanese Patent Publication No. 2012-153508). The conventional transfer device includes a cargo placement part for placing a cargo; a pair of forks each arranged on each side of the cargo placement part; and a pair of hooks each provided at a tip of each of the pair of forks.
For example, at the time of transferring a cargo from the storage shelf to the lift stage, first, each of the pair of forks moves forward along each side surface of the cargo placed on the storage shelf, and at the timing in which each of the pair of hooks gets over the rear surface of the cargo, each of the pair of hooks is rotated inward. Subsequently, with each of the pair of hooks being caught on the rear surface of the cargo, each of the pair of forks moves backward, and the cargo is thereby transferred from the storage shelf to the cargo placement part of the lift stage.
However, in the foregoing conventional transfer device, a space occupied by the pair of forks is relatively large, thereby causing restrictions on a space for placing a cargo on the cargo placement part, which is problematic.